In our earlier U.S. Pat. No. 3,961,183, we have proposed a twilight-responsive switch characterised in that it is composed, on the one hand, by an electronic circuit constituted in the case of a supply of continuous current, by a voltage divider bridge comprising a fixed resistor and a variable resistor constituting the photoresistance, by an amplifying stage and a bistable trigger circuit which controls, following each change of state conditioned by the illumination of the photoresistance, and by the intermediary of a changeover switch and a transistor amplifier, a motor, and, on the other hand, by a speed-reduction gearing meshing with a pinion fixed upon the shaft of this motor, by cams rigid with the final pinion shaft of the speed-reduction gearing, and by one or more contacts closing or opening one or more illuminating circuits, this electro-mechanical arrangement, by its design, permitting easy achievement of a duration of delay in the range from a few seconds to many minutes.
The present invention has as one object to facilitate a modification of construction of a twilight-responsive switch, permitting with simple and low-cost means, and with a minimum of bulk, the controlling of an electric circuit, particularly for illumination, with an adequate sensitivity.